The lower chamber ellipse

The interactive drawing shows the secondary master ellipse correctly placed, one quarter of its circumference above the lower level of the foundation plinth of the pyramid, with its half circumference base line highlighted in green and extending into, and along the floor of, the tunnel at the back of the niche carving on the chamber's east wall.

This ellipse is a cross section being formed from a 3D model of the Earth which is vertically above the temple on the east face of the pyramid and therefore outside of the physical structure of the building. When viewed from the east the ellipse appears to be located inside the lower chamber, but in reality is located in front of the east face of the building.